Gas turbines, operating under highly varying speed and load conditions, such as in automotive plants including a separate power turbine, are often provided with a guide apparatus comprising adjustable guide vanes. Such vanes are especially important in turbines having several rotors mounted upon separate shafts, being interconnected to permit power transfer, and fed with gas from a common producing unit. An adjustment of the guide vanes will make possible a distribution of power between the individual rotors. A disadvantage of most known designs of adjustable guide vanes is, that an adjustment of the vane will bring about an alteration of the angle of entrance, as well as of the angle of exit, which sometimes is undesirable.